The present invention relates to a loom.
Looms comprising heald devices of shafts are known, in which for the movement of the heald devices, levers are used. The levers have pivot axes which are aligned with one another and extend at right angles to the planes spanned by the heald devices. When a greater number of heald devices is present in such looms for the weaving of patterned fabric, different heald devices are frequently displaced different distances from their rest positions in the formation of the sheds in order to attain a favorable deflection of the warp threads. In order to produce these different displacements, the levers operatively connected with the heald devices have different lengths. The levers have drive output points, where the levers are connected with the heald devices, which are in most of the levers inevitably removed relatively far from the plane of symmetry of the center plane which extends through the centre points of the heald devices parallel to the direction of motion of the heald devices and at right angles to the planes spanned by the heald devices. In a known type of loom, the levers at the drive output points engage parts which are rigidly fastened to the heald devices. In operation, turning moments arise in respect of the center points of the heald devices. These turning moments must be absorbed by heald device guides and therefore cause noise, increase the wear and limit the maximum possible weaving speed.
In another loom, the levers are connected with the heald devices through flexible tension ropes. Although it is possible in that case to deflect the tension ropes by means of rollers and to fasten the tension ropes to the heald devices in the plane of symmetry or central plane, the additionally necessary deflecting rollers cause the manufacturing costs to be increased. Moreover, tension ropes deflected over rollers tend to deflect out laterally at great speeds, whereby the maximum weaving speed is limited.